/**
 * 双向链表 类
 */
public class DoubleListNode {
    /**
     * 结点值
     */
    int val;

    /**
     * 前驱结点
     */
    DoubleListNode prev;

    /**
     * 后继结点
     */
    DoubleListNode next;

    public DoubleListNode() {

    }

    public DoubleListNode(int x) {
        val = x;
    }

    public DoubleListNode(int x, DoubleListNode prev, DoubleListNode next) {
        this.val = x;
        this.prev = prev;
        this.next = next;
    }
}
